Process for removing metals from petroleum with an aromatic sulfonic acid



U fll States Patem a.

3,082,167 PROCESS FOR REMOVING METALS FROM PETRO- LEUM WITH AN AROMATICSULFONIC ACID John G. Erdman, Allison Park, Par, assignor to GulfResearch & Development Company, Pittsburgh, Pa., a corporation ofDelaware N Drawing. Filed July24, 1961, Ser. No. 125,969 5 Claims.v (Cl;208252) This invention relates to a process for treating mineral oilsand more particularly to a process for reducing heavy metal contaminantsespecially the porphyrin metallo complex content of mineral oils.

Vanadium, nickel and traces of other metals including iron and copperhave been detected in crude oils and in various petroleum distillates,some crude oils containing up to 1000 parts per million, or more, ofvanadium. The presence of these metals in catalytic cracking chargestock is undesirable in that they adversely affect the effective life ofcrackingzcatalysts. These metals are undesirable in residual fractionsused as fuel because of their tendency to cause corrosion and pitting ofmaterials of construction with which they come in contact. For example,-thepresence-of vanadium in residual fuel oils results in corrosion andfouling of high temperature boilers and the blades and heat exchangertubes of gas turbines.

A considerable portion of the metals selected from the group consistingof vanadium and nickel when pres ent in mineral oils, exist in the formof stable, volatile, non-ionic, oilesoluble, porphyrin metallocomplexes. The porphyrin metal-lo complexes are believedto be the onlyvolatile metallo complexes present in oils. The porphyrin metallocomplexes can be illustrated by the fol-lowing structural formula whereM is vanadyl (V=O) and nickelic (Ni).

The physical and chemical characteristics of the porphyrin metallocomplexes coupled with their presence in mineral oils in small amounts,has rendered their removal from, oils containing them extremelydifiicult.

Porphyrin metallo complexes occur in crude oils obtained from manygeographic locations. In preparing distillates from such crude oilsaportion of these complexes passesinto the products. It hasbeen'ascertained that the porphyrin metallo complexes possess sufiicientvolatility and thermal stability to distill over with petroleumfractions without decompositions. .Regardless of whether the porphyrinmetallo complexes are introduced into the distillates by' distillationor entrainment their a presence is highly undesirable.

Because of their neutral and oil-soluble. character, the

\ .porphyrin metallo complexes of the type occurring in 3,082,167Patented Mar. 19, 1963 are ineffective. The porphyrin complexes ofvanadium and nickel are so stable thermally that their destructionwithout substantial modification of the oils in which they occur isdifiicult. The aromatic hydrocarbon and nonhydrocarbon portions of crudeoils and other petroleum stocks including distillates are adsorbed morereadily than the porphyrin metallo complexes on polar adsorbents such asclay thus preventing removal of the complexes in this manner.

Attempts have been made to reduce the. porphyrin metallo complexes incatalytic cracking charge stocks by cutting the crude at temperaturesbelow which the metallo complexes pass into the distillate. While suchattempts to control the porphyrin metallo complexes in the distillateshave been at least partially successful, the amount of cracking chargestock obtained from a crude oil is materially reduced.

I have now discovered that heavy metal contaminants including theporphyrin metallo complexes can be removed from a mineral oil containingsuch contaminants by treating the contaminated oil in the liquid phaseat a temperature of about 100 to about 250 C. with an aromatic sulfonicacid which is liquid at the treating temperature. Under theseconditions, the. aromatic sulfonic acidsform a complex with the heavymetal contaminants. The complex. thusformed and excess sulfonic acidsettles from the oil in the form of a precipitate when the oil is cooledto room temperature or below. Upon separating the precipitate from theoil, an oil is obtained having a substantial reduction of heavy metalcontaminants. Thus, the process of the invention elTectively removesheavy metal contaminants, such as vanadium and nickel includingporphyrin inetallo complexes from a mineral. oil.

The aromatic sulfonic acids which can be employed in the process of theinvention. are" the monoand polysulfonic acids of aromatic hydrocarbonsand the monoandtpoly-sulfonic acids of the lower alkyl substitutedaromatic hydrocarbons. Representative aromatic sulfonic acids-thusinclude' b'enzenesulfonic acid; p-toluenesulfonic acid; diandtrisulfonic acids of. toluene; 0-, mand pxylene sulfonic acids;ethylbenzene sulfonic acids; mesi tylene sulfonic acid; and mono-, di-,triand tetrasulfonic acids'of naphthalene.

The present process isgenerally applicable to all types ofmetal-containing mineral. oils especially petroleum oils including bothpetroleum crude's and fractions thereof whether derived frompa'raflinic, naphthenic or asphalt base stocks which may contain up to1000' parts per million or more of contaminating metal. Thus, theprocess can be applied not only to metal-contaminated crude petroleumoils and virgin-stocks obtained from crude distillation untis, but alsoto metal-contaminated products obtained from typical hydrocarbonconversion processes such as cataly-ticcracking, hydroforming, steamcracking, and coking. While the process of the invention can be appliedboth to petroleum residual fractions and overhead fractions ordistillates, the process of the invention is particularly applicable topetroleum distillates.

In accordance with the present invention, substantial removal of'theheavy metal contaminants from a petroleum oil containing the same iseiiected by intimately contacting, the contaminated oil with thearomatic sulfoni c acid for a time and in an amount sufficient to form acomplex between the aromatic sulfonic acid and a substantial portion ofthe heavy metals in the. oil at a temperature of about to about 250 C. Atemperature of 100 .C. or more, is desirable in order to assuresubstantially anhydrous operating conditions. "The use of an anhydroussystem is desirable in that the presencejof water tends to inhibit thereaction and thereby increase the amount of the sulfonic acid which mustbe used. The reaction mass is then cooled, usually to room temperature,whereupon the aromatic sulfonic acid-heavy metal complex readilyprecipitates from the oil. Separation of the precipitated complex fromthe oil can be effected by any known means such as, for example, by

1 filtration, decanting, centrifuging and the like.

The amount of the aromatic sulfonic acid employed is that amount whichis at least sutficient to saturate the contaminated oil at theparticular treating temperature employed. While the aromatic sulfonicacids are generally considered to be insoluble in oil, they are solubleto a small extent at room temperature and to a greater extent attemperatures of 100 to 250 C. Generally, amounts ranging from about 0.05to about 1.0 weight percent based on the contaminated oil are sufficientto completely saturate the oil at temperatures of 100 to 250 C. While anamount greater than that which is soluble in the oil can be used, suchan amount is undesirable for economic reasons. Therefore, I prefer touse an amount which is just sutficient to form a saturated solutionthereof with the oil at the treating temperature employed.

The treating time depends upon the amount of metal contaminants presentin the oil, the intimacy of the contacting during the treatment and thetemperature at which the treating operation is conducted. In order tokeep the contacting time at a minimum, thorough commingling of thereactants is desirable. I have found that when treating a substantiallyparalfinic oil containing a relatively small amount of metal as, forexample, 40 to 50 parts per million of etioporphyrin vanadium complex, acontact time of about one minute is ordinarily sutficient at 180 C. toeflect a substantial reduction of the porphyrin vanadium complexcontent. Where the oil to be demetalized is so viscous that intimatecontacting with the aromatic sulfonic acid is difficult, it isadvantageous to dilute the oil with a suitable hydrocarbon solvent. Thesolvent should not be volatile at the contacting temperature andpressure employed. The volatility of the solvent, however, should besuch that it can be readily separated from the oil.

The process of the invention is illustrated by the following specificexamples:

Example 1 Into a flask equipped with a stirrer was placed 150milliliters of a 1:2 by volume white mineral oil: n-decane mixturecontaining 49 parts per million of etioporphyrin I vanadium complex. Thesolution was heated to about 180 C. in the presence of air. To thissolution was added 0.2 gram of benzene sulfonic acid which correspondsto about 0.18 percent by weight based on the contaminated oil mixture.The reaction mass was then agitated for a period of about one minute ata temperature of about 180 C. Thereafter the mixture was cooled to roomtemperature and filtered through a fluted filter paper to remove theprecipitated benzene sulfonic acidporphyrin vanadium complex. Thefiltrate was scanned on a spectrophotometer and the concentration ofetioporphyrin I vanadium complex in the filtrate was found to be about4.1 parts per million. The treatment with benzene sulfonic acid thusremoved about 92 percent of the porphyrin vanadium complex from the oil.

Example 2 Into a flask equipped with a stirrer was placed 150milliliters of a 1:2 by volume white mineral oil: n-decane mixturecontaining about 109 parts per million of etioporphyrin I vanadiumcomplex. The solution was heated to approximately 180 C. under a blanketof nitrogen. To this solution was added 0.17 gram of benzene sulfonicacid which corresponds to about 0.15 percent by weight based on thecontaminated oil mixture. The reaction mass was then agitated for aperiod of about one minute at a temperature of about 180 C. Thereafterthe mixture was cooled to room temperature and filtered through a flutedfilter paper to remove the precipitated benzene sulfonic acid-porphyrinvanadium complex. The filtrate was scanned on a spectrophotometer andthe concentration of the etioporphyrin I vanadium complex in thefiltrate was found to be 23 parts per million. The treatment withbenzene sulfonic acid thus removed about 79 percent of the porphyrinvanadium complex from the oil.

Example 3 Into a flask equipped with a stirrer was placed milliliters ofa 1:2 by volume white mineral oil: n-decane mixture containing 124 partsper million of etioporphyrin I vanadium complex. The solution was heatedto about C. To this solution was added 0.19 gram of benzene sulfonicacid which corresponds to about 0.17 percent by weight based on thecontaminated oil mixture. The reaction mass was then agitated While airwas bubbled through the oil until the mixture was cooled to roomtemperature. It was filtered through a fluted filter paper to remove theprecipitated benzene sulfonic acid-porphyrin vanadium complex. Thefiltrate was scanned on a spectrophotometer and the concentration of theetioporphyrin I vanadium complex in the filtrate was found to be about23 parts per million. The treatment with benzene sulfonic acid thusremoved about 81 percent of the porphyrin vanadium complex from the oil.

Example 4 In this example, a catalytic cracking charge stock of Maracrude oil was employed. Spectral examination of the crude oil showed itto contain 72.5 parts per million of porphyrin vanadium complexes. Asolution was formed by adding sufficient spectrally pure n-decane to 5.2grams of the crude oil to give a total of 25 ml. The solution thusformed was heated to about 156 C. To the heated solution was added 0.095gram of benzene sulfonic acid which corresponds to about 0.27 percent byweight of the solution. The mixture was shaken vigorously for one minuteand then cooled under tap water to room temperature in about twominutes. A benzene sulfonic acidporphyrin vanadium complex separated asa dark film on the walls of the treating vessel. The mixture wasfiltered through glass wool to remove the benzene sulfonic acidporphyrin vanadium complex which remained in suspension in the oil. Uponspectral examination of the filtered oil, it was found to contain only26.3 parts per million of porphyrin vanadium complex. The treatment withbenzene sulfonic acid thus removed about 64 percent of the porphyrinvanadium complex from the oil. In addition to removal of the porphyrinvanadium complex, examination of the oil showed substantial improvementin its color.

Example 5 Into a flask was placed 25 milliliters of a 1:2 by volumewhite mineral oil: n-dodecane mixture containing 101.6 parts per millionof etioporphyrin I nickel complex. The solution was heated to about 180C. To the heated solution was added 0.037 gram of benzene sulfonic acidcorresponding to about 0.204 percent by weight based on the oil solutionbeing treated. The mixture was then vigorously shaken for about oneminute and then cooled under tap water to room temperature in about twominutes. The cooled mixture Was then centrifuged to remove theprecipitated benzene sulfonic acid-porphyrin nickel complex. Thecentrifuged oil-dodecane mixture was then scanned on a spectrophotometerand the concentration of etioporphyrin I nickel complex in the mixturewas found to be about 6.4 parts per million. The treatment with benzenesulfonic acid thus removed about 94 percent of the porphyrin nickelcomplex from the oil-dodecane mixture.

Example 6 Into a flask was placed 25 milliliters of a 1:2 by volumewhite material oil: n-dodecane mixture containing 101.6 parts permillion of etioporphyrin I nickel complex. The solution was heated toabout 215 C. To the heated solution was added 0.026 gram of p-t-oluenesulfonic acid corresponding to about 0.143 percent by weight based onthe oil solution being treated. The mixture was then vigorously shakenfor about one minute and then cooled under tap water to room temperaturein about two minutes. The cooled mixture was then centrifuged to removethe precipitated p toluene sulfonic acid-porphyrin nickel complex, Thecentrifuged oil-dodecane mixture was then scanned on a spectrophotometerand the concentration of etiop orphyrin I nickel complex in the mixturewas found to be about 34.6 parts per million. The treatment withp-toluene sulfonic acid thus removed about 65 percent of the porphyrinnickel complex from the oildodecane mixture.

Example 7 Into a flask was placed 25 milliliters of a 1:2 by volumewhite mineral oil: n-dodecane mixture containing 101.6 parts per millionof etioporphyrin I nickel complex. The solution was heated to about 215C. To the heated solution was added 0.026 gram of Z-naphthalene sulfonicacid corresponding to about 0.143 percent by weight based on the oilsolution being treated. Themixture was then vigorously shaken for aboutone minute and then cooled under tap water to room temperature in abouttwo minutes. The cooled mixture was then centrifuged to remove theprecipitated Z-naphthalene sulfonic acidporphyrin nickel complex. Thecentrifuged oil-dodecane mixture was then scanned on a spectrophotometerand the concentration of etioporphyrin I nickel complex in the mixturewas found to be about 54 parts per million. The treatment withZ-naphthalene sulfonic acid thus removed about 47 percent of theporphyrin nickel complex from the oil -dodecane mixture.

The above experiments clearly demonstrate the effectiveness of theprocess of my invention in reducing the porphyrin metallo complexcontent of mineral oils. Similar results are obtained when the benzene,p-toluene-, or naphthalene sulfonic acids are replaced by other aromaticsulfonic acids including xylene sulfonic acids, ethylbenzene sulfonicauid, mesitylene sulfonic acid, as well as the di-, triand tetrasulfonicacids of naphthalene.

In addition to obtaining an oil of reduced porphyrin metallo complexcontent by the process of the invention, there is also evidence that thegeneral quality of the oil is improved as indicated by a decrease in thecolor.

While my invention has been described with reference to various specificexamples and embodiments it will be understood that the invention is notlimited to such examples and embodiments and may be variously practicedwithin the scope of the claims hereinafter made.

I claim:

1. A process for removing a heavy metal contaminant tacting thecontaminated oil under anhydrous conditions in the liquid phase at atemperature of about 100 to about 250 C. with an aromatic sulfonic acidwhich is liquid at the treating temperature for a time and in an amountsulficient to form a complex between the aromatic sulfonic acid and saidcontaminant, cooling the reaction mass to effect precipitation of thearomatic sulfonic acid-heavy; metal complex and separating theprecipitated complexi from the reaction mass to obtain a mineral oil ofreduced heavy metal content.

2. A process for reducing the porphyrin metallo complex content of apetroleum distillate containing the same comprising contacting saiddistillate under anhydrous conditions in the liquid phase at atemperature of about 100 to about 250 C. with an aromatic sulfonic acidwhich is liquid at the treating temperature for a time and in an amountsufficient to form a saturated solution thereof with said distillate atthe treating temperature employed, cooling the reaction mass to effectprecipitation of an aromatic sulfonic acid-porphyrin metallo complex andseparating the precipitated complex from the reaction mass to obtain apetroleum distillate of reduced porphyrin metallo complex content.

3. A process for reducing the porphyrin metallo complex content of apetroleum distillate containing the same comprising contacting saiddistillate under anhydrous conditions in the liquid phase at atemperature of about 100 to about 250 C. with about 0.05 to about 1percent by weight of an aromatic sulfonic acid which is liquid at thetreating temperature for a time sutficient to form a saturated solutionthereof with said distillate at the treating temperature employed,cooling the reaction mass to eilect precipitation of an aromaticsulfonic acid-porphyrin metallo complex and separating the precipitatedcomplex from the reaction mass to obtain a petroleum distillate ofreduced porphyrin metallo complex content.

4. A process for reducing the porphyrin metallo complex content of apetroleum distillate containing the same comprising contacting saiddistillate under anhydrous conditions in the liquid phase at atemperature of about 100 to about 250 C. with about 0.05 to about 1percent by weight of benzene sulfonic acid for a time sufficient to froma mineral oil containing the same comprising con- I form a saturatedsolution thereof with said distillate at the treating temperatureemployed, cooling the reaction mass to effect precipitation of a benzenesulfonic acidporphyrin metallo complex and separating the precipitatedcomplex from the reaction mass to obtain a petroleum distillate ofreduced porphyrin metallo complex content.

5. The process of claim 4 wherein the metal of said porphyrin metallocomplex is selected from the group consisting of vanadium and nickel.

References Cited in the file of this patent UNITED STATES PATENTS2,948,675 Case et al Aug. 9, 1959

1. A PROCESS FOR REMOVING A HEAVY METAL CONTAMINANT FROM A MINERAL OILCONTAINING THE SAME COMPRISING CONTACTING THE CONTAMINATED OIL UNDERANHYDROUS CONDITIONS IN THE LIQUID PHASE AT A TEMPERATURE OF ABOUT 100*TO ABOUT 250*C. WITH AN AROMATIC SULFONIC ACID WHICH IS LIQUID AT THETREATING TEMPERATURE FOR A TIME AND IN AN AMOUNT SUFFICIENT TO FORM ACOMPLEX BETWEEN THE AROMATIC SULFONIC ACID AND SAID CONTAMINANT, COOLINGTHE REACTION MASS TO EFFECT PRECIPITATION OF THE AROMATIC SULFONICACID-HEAVY METAL COMPLEX AND SEPARATING THE PRECIPITATED COMPLEX FROMTHE REACTION MASS TO OBTAIN A MINERAL OIL OF REDUCED HEAVY METALCONTENT.